1. Field of the Invention
The present invention generally relates to a metal etching method, a metal etching control method and a control device thereof, and more particularly to a metal etching method, a metal etching control method and a control device thereof which can precisely judge a total real etching time needed for each of a batch of metal films as performing metal etching to the metal films.
2. Description of Prior Art
Please refer to FIG. 1, which shows a diagram of that a substrate 100 carrying a metal film is conveyed in a metal wet etching machine 1 when LCD panel is manufactured. In the LCD panel manufacture, the metal wet etching machine 1 is used for executing a wet etching to the metal film. The metal wet etching process is to load the substrate 100 carrying the plated metal film (metal layer) in an etching bath full of acid solution. Then, etching is performed to the area unprotected by the photoresist to obtain the patterns protected by the photoresist. Before the metal wet etching machine 1 is used to perform etching to a batch of metal films. One in the batch of the metal films is selected as being a sample metal film and to acquire an etching end time of the sample metal film. Two ways of performing the etching end time detection exist in the industry nowadays. One is shown in FIG. 2, which shows a diagram of that a work 150 executes a random check for judging the etching end time of the metal films with unaided eye by experience according to prior art. The other is to acquire the etching end time of the sample metal film through the sensor 104 of the EPD (End Point Detector). The etching end time is defined as the period of time from loading the substrate 100 into the etching bath full of acid solution till the sensor of the end point detector detects the metal film penetrated by the light (the substrate 100 is employed for carrying the metal film). The working theory of the end point detector is based on the light reflection/penetration. As the metal film remains on the substrate 100, the light generated by the sensor of the end point detector is still reflected by the metal film because the light cannot penetrate the metal film. The end point detector judges that the end point time of the metal film has not arrived hereby; as the metal film carried by the substrate 100 is etched completely, the light generated by the sensor of the end point detector can penetrate the substrate 100 and is not be reflected because the light can penetrate the substrate 100. The end point detector judges that the end point time of the metal film has arrived hereby.
After the etching end time is acquired, the etching is now performed to the batch of the metal films. To prevent the situation of unequal etching rates and the remaining metal film, generally, an over etching time is added on after the etching end time, which is a total real etching time. The definition is: total real etching time=etching end time+(etching end time×over etching ratio) to prevent the situation of remaining metal film. For example, the acquired end point time of the metal film is 100 sec, and the setting ratio is 42%. Then, the total real etching time for each of the metal films is set at 142 sec.
However, some drawbacks still exist in the aforesaid method. Among the batch of the metal films, it is impossible that all the thicknesses of the metal films are the same. Under such circumstance, if the etching with the same total real etching time is performed to each of the metal films, the thinner metal film will be over etched and the thicker metal film will not be etched enough and consequently results in the unstable etching quality.
Therefore, there is a need to provide a metal etching method, a metal etching control method and a control device thereof for solving the existing drawbacks of aforementioned prior art.